System of motor control.



110.894,233.- PATBNTBD JULY 2O, 1908. W. J. RIOHASDS. SYSTEM OF MOTOR CONTROL.

-APPLIOAMON FILED 1111.31, 1907.

' z SHEETS-Smm 1.

@SSS

No. 894,233. l PATENTES JULY 2S', i908, y W. J. RICHARDS.

i SYSTEM 0Fi MOTOR CONTROL. y

APPLICATION FILED JAN. 31, 1907.

z SHEETS-SHEET 2.

Unrrn WALTER J. R1CHARDS, OF NORWOOD, GHI() ASSIGNOR TO ALLlS-OHALMERS GOMPANY,A

" ACORPORATION 0V NPV.' JERSEY.

SYSTEM OF MGTOR CQN'IROL.

Application filed `fanuary 31 State of Ohio, have invented certain new and 4useful Improvements in Systems of Motor Control, of which the following is a full, clear,

r .and exact specification,l

My `'nvention relates to motor control systems, Aespecially as applied to teaser systems of printing press control.

In operating certain kindsof machirnery, suchas perfecting printing presses,it is neoessary that the starting and stopping be accomplished Without shock. An admirable arrangement for accomplishing this is set forthin the patent to Burke No. 611,588,

Sept. 27, 1898. It is often desirable, however, that machinery be controllable from a number oi different points or stations about it. 1t is also 'desirable that in ease conflicting operations are simultaneously sought, only the most conservative of the operations desired will be obtained .g that is, in case it is simultaneously sought to go faster, to go slower, and -to sto-p, a stopping will result, While a slower operation may be obtained regardless of attempts to obtain a faster operation. Also, a quick stop should be obtain# able Without shock. Moreover' it is often advantageous to require no niceties of n1 anipulation by the operator, so that in case of emergencythe desired object will not be defeated by too much or too little movement or force on the partei-the operator.

Itis the object of my present invention to provide a motor control system in which all the advantages ot' the control system set forth in the Burke patent are eombined'with those above stated.

My invention therefore broadly comprises a system of motor control consisti'ig of a motor to be controlled, a converter," means for co" necti"-ig said motor to a source of current either directly or through the converter, and a push-button controlling. system for said means. y P

lu another light my invention comprises vthe combination oi' a motor, a main controller therefor, and ama-ster controller for the 'maia controller "i'imprising a plurality of 'push-buttoi's lor aeeompllshlug dill'ei'e-.t re- Specification of Letters Patent.

ententes-July as, ieee.

, 1.907. serial No. 355,163.

buttons are depressed to obtain conflicting results only that one of the depressed pushbuttons which seeks the most 'conservative running of the motor will be effective.

Other-features of my invention Will app ear from the following description and accompanying drawings and will be particularly pointed out in the claims.

Figure 1 is a diagrammatic view showing one embodiment of my invention; Fig. 2 is a section on the line 2&2 of Fig. 4, showing onev arrangement of a controller station; Fig. 3 is a section on the line 3 3 of Fig. 2 Fig. 4 is a sect-ion on the line 4-L1of Fig. 2 and Fig. 5 is a sectional view showing the means for retaining the controller arm in any desired position.

The main motor 10 is arranged to be controlled by a movable arm 11, willich in its ditfer'ent positions is arranged to connect the motor 10 to the mains 12 and 13 either directly or through a'converter 14. 1n the mains 12 and 1?' there may be manually operated switches 15 and 15il if desired, While betweenV the main 12 and the various circuit-s is a solenoid-operated switch 16. The solenoid 17 of the switch 16 is conuected'between the mains 12 and 13 through a switch 1S which is closed only when the arm 11 is in itr-.glowest position,l and through manual switches ai', )f

e .a. These latter switches are around the press or othercontrolled mechanism. There may be any number of these stations, which are the master controllers. When any one of the switches av', L, c", .-n is open -the solenoid 17 is denergized. When all of these switches are closed, and the arm 11 is in its 1 lowest position to close switch 18, the solenoid 17 is energized to close the switch 16. 16 not only completes the various controlled and. controlling circuits, but also short-eircuits the switch 18, so that when the switch 16 is closed the circuit of the solenoid 17 remains complete regardless of the position of the arm 11.

The arm 11 is biased toward its lowest position, either by gravity or a spring 20 or bothJ while it may be moved upward by a solenoid 21. provided for manual operation of the arm 11. 'A coil 22 is wound in the support 2S of the arm 11 and when energized acts as a magnetic The closing of the switch It desired, a handle 11a may be.

3 iii* respectively.

clutch to hold the :irni l1 in :in v position in which it univ lmppen to he. yThis struct'nrf.\ is hes-t iiidiinited iii,yl"i'. 5. dash-pot 21's arranged to retzird l'iotli the npwzird :ind the downward movement of the :iim l1. Stops (l1 :ind o2 limit tht` movement of the :irn'i 11. At the stuiioiis A. B, t, :ire other swim-hes (Il. X", .11 respectively, und :ils-o. except :it stiitioiii\,switclies b3, ri",

lizicli ot these switches cooperates with two tiXed contacts :is shown. 'lhe switches r'und /f,c`f;ind c, .fnzind n :ire mechanically connected to move together und :ire hiiised to the positions in. which they :ire shown in lull lines. Hereai'ter when it is stiited that :my ol the switches b2, c2, .n2 :ire moved to ai certziiii position it is to he understood that their respective associated switches Z13, cf",'. .n3 :ire correspondingly moved. vlien the switches a, b2, c2, fnl' :ire in their normal position, and the switch ]t is closed, the circuit of the coil 22 is conipleted, :ind said coil holds the arni 1.1 in *whatever position it may happen to be. l'i'lien :my switch. e, lf, c2, .ne is in its lowest position, :is shown in dotted lines at station l\', the coil 22 is denergized, Aand, except in certain cases l'iereinzifter described, the solenoid 21 is energized, thus causing the arm 11to niove upward. vWhen any switch o, 122, c?, .n2 is in its middle position, is indicated in dotted lilies it station B; vboth the coil 22 und the solenoid 21 :ire denerY `fixed :ind the spring 2t) moves the erifirll downward. i

The converter 14 is here shown :is :i teaser or step-down motoisgeiierzitor, comprising a motoismnniture 2.3 :ind u generator armut'urc 2G together with their respective field windings 27 :ind 28. Any other desired forni oi rmiverter inzivv he used. In the lower puri' oi' lits movement the firm 11 connects the motor ormziture 1t) to the teaser generat- 'tor iirnniture 2o rind 'varies the voltage of seid tciiser generator hy varying its"speed rind teld strength successively. Further up in its movement the zirngi 11. connects the iotor :ir-nurture 1t) to the niiiins 12 sind 13 und vitries the resistance in circuitwitli sziid niotor iii'niitture. The 'ield winding' 29 oi the mitin motor is always supplied directly troni the moins 1.2 :ind 13 whenever the switch 16 is closed, but the resistance o1 its circuit is viiried during the operation o1 the 1irni 1 1. To :iccoiiiplish these results, the `(irni 11 lios two electrically distinct parts 3) and 31 preter- :ihly insulated fromy tlie rest olt the firm, The pzirt 3() controls resistance 3.12 :ind 32 in the circuit o1 the teaser motor armature 25, :ind :i resistance 33 in the circuit of the teaser gonerzitiir lield winding 28. The contacts oi the resistiinces 32 und l32lL may he crosscounewted il' desired :ind only one resistance used. 'l`lie pzirt i connects the :Lrimiturc l() to the tensor generator 213, :ind to the miiins 12 rind 1&1 through :i resistance 34 and vziries sind. re sistxince. Near the upper end ol' the movement ot the arni 11 the puri 31 :ilso 'viii-ies :i resistiinre 35 in the circuit oll the liold winding' 2t) of the nniin motor, ln order to in eoniplisli this hitter result, u si' itch Ilo, v. hiru normzill)Y eoi'inects the lield winding :iii hetween the niiiins 12 and 123 ffihout thtx iner'- Yention ol any resistance. is optiud h v :i piii 37 inthe iirm 11 in its upiizird movemriitV :is siiid :irm reaches the lowest' rontiirt ossot'izited with theresistzincg 532'), :ind is closed hi siiid pin ris seid ziri'ii in its doii'nrzird niort nient is :ihont to lezive sind louest contiirt.

The operation o1: the syst em is is l'ollo'vI The switches 15 und 13" heingil closed. the motor 1t) is started when the hist oll thil Switches at', Il, r, .li/ is closed. The closure of this switch, iis l, provided the :irm 11 is in its lowest position to close the su itch 18, energizes the solenoid 17 to close .the switch 16. rl`he closure olI the switch 'l coni )lotes thc circuits of the miiin motor lield win inor 29, the teaser motor lield winding 27, the teaser inotor :irnniture 25 through the entire resistance 32, und the teaser renerzitor field winding 28 through the entire resistance 33. It also short-circuits the switch is so tlizit'the circuit of solenoid 1T is not' hrohen when the arm 11 begins to more upwzird. Moreover, it puts the circuits oil the coils 21. and 22 under the control ol' the proper switches :it the various stzitions such :is switches b2 sind b :it station B. Unless some of these switclv have been nioved l'roni their nornnil positions, the circuit ol coil 22 is completed by the closure o1l the switch lo, but this coil serves no purpose tit this partie ulm' point in the operation, liecziusc the :irm 11 is held against further downward iiioveinentby the stop G1. The motor iiriiiiitnre l() is connected across the 'i'.euser generiitor armature 26 by means ol' the part 211 ol' the erin 11.. Thus et this time the motor :irnim ture 10 is connected to the miiins 12 :ind 1:3

through the converter 11.

The closing of the switch it causes the teaser motor 2F to start and to drive the teaser generator zirnniture 2o vto suppl)v the motor armature 1() with current :it :i low voltage. This cziuses tliei'iiotor 1t) to stzirt gradually. llz it is desired to go 'l'zister one oi the switches al, of, c, xn? is moved into its lowest position, :is shown in dotted lineszit station N, :ind dei'liiergixcs the retainingr coil 22 :ind energizes the solenoid 21, 'l`lie letter hegrins to move the zirm 11 slowliY upwzird, hut continues to do so'onlyY so loner iis the switch n? or itsl imilogue is held in its lou` est position. Upon the release oll the switch 'n2 liv the operator, this switch returns to its noriniil or upper position, :ind dei'inergizes solenoid 21 :ind energizes retiiininjr coil 22 to hold the zirin 11 in wlnitever iosition it luis reactie( l.

.thus further increasing the voltage impressed 'starting up the-teaser 14 As thearm 11 is moved upward, the resistance 32 is gradually cut out to increase the speedof the teaser motor 25 and consequently .the voltage impressed upon the motor armature '10 by the teaser generator 26. After the'vresistance 32 has been entirely cut out to bring the motor 25'up to full speed, the resistance 33 is gradually .cut out of circuit with the teaser generator eld winding 28,`

upon -the motor armature 10 generator armature 26.

When the resistance 33 has been fully cut out, the voltage of the teaser generator is at its maximum. Continued upward movement ot the arm 11 beyond this point causes the part 31 oli-said arm to connect the armature 10 to the mains 12 and 13 through the entire resistance 34, this resistance also serving to reduce the volta e impressed on the motor armature 10 by tle main source of current to by the teaser that of the teaser generator 26. Shortly.

afterthe armature 10l has been connected to the mains through the resistance 34, 'the part 31 of the arm 11 disconnects it from the armature 26. Continued upward movement of the arm 11 from this point cuts the resiste' i wlth the armature 10,-

ance 34 out of circuit thus increasing the voltage impressed thereon and gradually increasing its speed. This movement also inserts the resistance 32a in the circuit of the motor armature 25 to slow it down and inallydisconnectsthe converter or teaser 14.

When'the entire resistance 34 has been. cut out the full voltaire of the mains 12 vand 13 vis impressed upon t 1e motor armature 10, and further movement of the arm 11 beyond this point causes the and the part 310i said arm to cut the resistance 35 gradually into circuit with the field coil 29.to further increase the speed of the main motor. y l.

When the arm 11 is caused to move downward by moving one of the switches (L2, b2, cf, .n2 to its middle position, asshown in dotted lines at station B, and holding` it there, the reverse ot' the actions above described takes place. Thus the motor 1 0 is slowed down by iirst increasing its field strength, the switch 36 being` closed the pin 37 when the entiro resistance has been cut out, then cutting;l the resistance 34 into circuit to decrease the potential impressed on its armature, then and connecting the 'motor arrnatru'e 10 to the teaser generator armature and disconnecting` it from .the mains, and finally diminishing first the teaser generator field strength and thenthe speed of said teaser.- This downward movement may he stopped at any point by releasing. the switch if' or its analogue; The above is the slowing down .operation under normal conditions. But il an emergency switch, as c', is opened, the coil 17 is denergized and the pin 37 to open the switch 36' switch 16 opened to interrupt all circuits supplied by the mains 12 and 13, and, it the motor armature 10 was connected to said mains, to close the circuit of said armature upon itself through so much ot the resistance 34 as was not in circuit` as the switch 16 opened. This causes the armature 10 to act as a generator armature to excite its own iield winding 29, and to slow down rapidly, by reason of the braking e'tect thus produced. As the motor slows down and the arm 11 descends, the-resistance 34 which was in the closed circuit of the armature 10 is graduallyv cut out, so that asthe electromotive torce generated by the armaturedecreases the resistance in the circuit is also decreased to maintain the braking current more nearly constant. The switch 16, once opened because of the opening of an emergency switch, as c, Vcannot he closed again until the arm 1L has reached its lowermost position and closed the switch 18. The arrangement of switches at tbe various stations A, 13,0, .N is such that it there is a conflict of opinion between different operators as to the proper thing to be done, the most conservative operation desired will be obtained. Thus if one operator desiresan immediate stop he may obtain it by opening his emergency switch (1.26', c. .or n, as the case maybe, thereby causing the opening of the switch 16 to deprive vall the operating circuits of currents so that it matters not whether or not any'oi the other operators have moved their switches for a faster or a slower movement. It' diii'erent operators re'- spectively desire to ge faster and slower, the one who desires to go slower, say at station Bf will revail, because by moving his switches and b3 to their` intermediate positions, as shown in dotted lines, he not only interrupts the circuit `of the retainingr coil 22 to allow the arm 11 to descend, but also renders it impossible for the circu it of either solenoid 21 or retaining coil 22 tobe completed at any of theotherstationsA,C, .N. It two or'more operators desire to go slower and move their switches, say b2 and n2, to intermediate positions, the circuit of coil 22 will be broken and additional breaks made in the circuit of solenoid 21, and the arm 11- will descend to cause a slowing down of the motor 10; It a number of operators should all desire Ato go faster, and move their switches, say t? and f/zf, to their lowest positions, as indicated at station N in dotted lines', the circuit of coil 22 will he broken at two points and the circuit of coil 21 willbe'comnleted through the switches n and bzin their owest positions and c and az 1n their uppermost positions, and the arm 11 will be moved upward to cause a speeding up of the motor with my system'conservative running of the press is favored., while control may be obs tained troni any desired number-'ot points.

With the arrangement set torthin Fig. 1,

are depre it might sometimes happen that an operator in his excitement would move one of the controlling switches whichhas several operative posit-ions either too far or not tar enough. Thus for instance the switch if might be moved only to middle position when the operator intended to move it to its lowest position, or vicel versa. To avoid this liability of confusion, I have devised the arrangement shown in Figs. 2, 3 and 4, in which one ot' the stations, here taken as B, has the same three switches b, b and Z13 as shown at station B in Fig. 1. The switches in Figs. 2, 3 and 4 are intended to be operated by various push-buttons 41, 42, 43 and 44. The switch b2 is arranged to be closed by pushing in the starting push-button 41 and to be opened by pushing in the stop push-v button 42. AA spring 45 is provided for giving this switch a snap action. The two push-buttons 43 and 44 are arranged to be held in their` outer position by a double leafspring 46, but either of them when depressed will move both switches b2 and b3 downward, the movement ot' the switches caused by depressing the button 43 being greater than that caused by depressing` the button 44 because of the ditlerent distances ofthese push-buttons from the pivotal or supporting points of the switches b? and b3. By depressing` push-'button 43, the switches b2 and b3 are moved out of engagement with their upper contacts 47 and 4S respectively, to-

, ward which they are biased, and into engagenient with their lower contacts 49 and 50 respectively, this being equivalent to movingl the switches b2 and L in Fig. 1 to their lowest positions, By depressing pusli-l utton 44, the twoswitches 7)"2 and b are moved away troni their upper contacts 47 and 48 respectively, but are not moved tar enough to en gage the contacts 4l) and 5. respectively. Moreover by means ot an extension l of the push-button 44, the contacts 49 and 5() ,d so that they cannot be engaged by the switches b2 and o even though the push-button 153 is also depressed. rlhis is still further to insure cmiservative running of the pressA ln case an operator in his cxcitement pushes in thc two buttons 43 and 44, the circuits ol both coil '22 and solenoid 21 will bc broken to cause the motor 1t) to slow down. Should the push-button 42 bc depressed al thc same time as either or both ol the push-buttons 43 and 44, the switch 16 will bc caused to open to obtain an emergency slop ol'Y the motor and only the push.- button 4; will bc clicctivc. Il. is impossible to siinnllancousl)Y depress push-buttons 41 and -l-Z. Should push-buttons 41 and 43 be sinndlanconsli' depressed with the arm 11 in its 'lowest position, thc switch 16 -will be closed and the arm l l caused to move slowly upward to increase thc speed ot the motor.

l 'lhcsc two puslnlniltons are not conflicting` Should the push-button 41 be depressed at the saine time the push-button 44 or both 43 and 44, with the arin 11 in its lowest position, the motor will start but the arm 11 will not move, the push-button 43, ii depressed, being rendered ineiiective because the push-button 44 is depressed andthe push-but`ton 44 being ineffective because the arrn 11 is already in its lowest position. However, it would hardly ever happen that the starting"`. push-button 41 would be pushed in by i'nistake, because when the motor is operating -and there is liable to be confusion this pushbutton isalways depressed. The push-buttons 41, 42, 43 and 44 together with the switches which they control. are preferably arranged in a single box or housing 5;. though this is not necessary.

Terms which indicate position or direction, such as "lowest,l upward, downward, etc., refer to the drawing only and are no intended to liniit the actual structure. The d iHerent parts may be placed in an] desired position and moved in any desired direction.

Many modifications may be made in the .precise arrangements herein shown and described and all such which do not depart from the spirit and scope of my invention l aiin to cover in the following claims.

l/Vhatd claim as new is 1. Infioinbination, a motor, a source ol' current supply, a converter, a niain controller arranged to connect said motor to the source of supply either directly or through the converter, and a plurality of electrically interloclied push buttons for controlling said main controller.

ln coinbinatioaan electric motor, a supply circuit, a converter, a rnain controller for connecting the motor with the supply circuit either directly or through the converter, and a plurality of master controllers for said main controller, each oi said master controllers comprising a plurality oi switches.l

3. "lhc combination with an elec-tric motor, oi a supply circuit, a converter, mea-ns tor connecting the motor with the supply circuit,

means vfor breaking the converter circuit at' an intermediate spccd of the motor, and u push but-ton system ol control for both ol said means.

4. T he combination with anclcctric motor, of a supply circuit, means for connecting the motor with the supply circuit, a controlling rheostat in said supply circuit, a converter in circuit with the motor and with said supply circuit, means 'for breaking thc converter circuit at an intermediate speed oi inc met or. and a push button system of control lor both oi said means and said rheostat.

5. The combination with an electric motor, oi' a supply circuit, means tor connecting the motor with the supply circuit, a controlling rheostat in said circuit, a converter, means for intcrposing said converter between said .will prevail.

sea-,esa

converter and for cutting the converter outl of circuit at an .intermediate speed of the motor, and a plurality of master controllers for said means, each of said master controllers comprising a plurality oi switches.

7. The combination v'ith an electric motor,

of a supply circuit, a converter, means forv connecting the motor with the supply circuit either directly or through the converter and' for varying` the voltage impressed on the inotor with either connection, and a plurality of master controllers 'for said means', each of said master controllers comprising a plurality of push-button switches..

8. In combination, an electric motor, two sources of current supply, means Jfor con-- necting said motor to either of said sources separately or in parallel, and a push-button system ot' contro. for said means.

9. ln combination, an electric motor, 4a plurality of sources of current, means for connecting` said motor to any of said sources and 'for varying,` the potential impressed upon the motor by any of said sources, and a plurality el push buttons for controlling said means.

l0. In combination, a motor, a source of supply, a converter, means 'for connecting the motor to the source oi supply either directlyl .ti irerunning oi the motor will prevail.

il. In combination, a motor, a main controller therefor, a plurality ci push-buttons for controlling said main controller, and con.- nections whereby in case more than one push-button is depressed at any one time, the push-button which normally causes the most conservative operation, oli. the motor will prevail;

l2. In' combination, a motor, a source of supply, a converter, a main controller for connecting,r said motor to said source of supply eilherdiiectly orthrough the converter, a plurality of master controllers for the main controller, and connections whereby in case more than one master controller is operated at a time that one Whicli'is operated to obtain most conservative runninf l ot' the motor ln combination, a motor, a supply circuit, a converter, a main controller loi connecting; the motor to the supply circuit' either directly orthrough the converter and I ineffective.

'for varying the voltage impressed upon the motor with either set of connections, a plurality of .master controllers for the main controller, and connections whereby in case different master controllers are operated to obtain conflicting results the most conservative results sought for will be obtained.

le'. ln combination, motor, a main con- *,ti'oller therefor', a master controller for the main controller, said master controller comprising a plurality of push-buttons ,for obtaining different results, and said push buttons being so connected and arranged that in case conflicting" push-buttons are simultaneously depressed only that one ofthe depressed push-buttons which calls for the most conservative running of the motor will be effective.

'15. In combination, a motor, a main controller therefor, a master controller for the main controller, said master controller having slower and faster push buttons, and means whereby when the slower push button is depressed the faster push button is rendered ineffective. t 16. l-n combination, a motor, a main controller therefor, a plurality oi master controllers for the 'main controller, each of said .master controllers having,- slower and faster push buttons, said push buttons being so connected. and arranged that when any slower7 push button is depressed, the faster push buttons are all rendered l?.V ln combination, a motor, a main controller' therefor, a master controller' for the main controller, said master controller having slower-Q faster, and "stop push buttons, and means wherebywhen the stop push button is depressed, the other'push buttons are rendered ineffective.

18. In combination, a motor, a main controllentlierefor, al plurality of master controllers for the main controller, cach of said master controllers having sloWer faster, and stop push buttons, said push buttons being so connected and arranged that when any stop push button is depressed, all the faster and slower push buttons are rendered ineffective.

1'9.' In combination, a motor, a main controller .therefor biased toward'movement in one direction, Van electromagnet for moving said controller steadily in the other direction,

' a second electromagnet for holding the coni troller in any position againstmovement in -either direction, and a master controller for controlling said two electroniagnets, said master controller comprising a plurality of push buttons.

20. ln combination, a motor, a main controller therefor biased to. move in onel direction, an electromagnet for moving said controller in the other direction, a second electroinagnet for holding said controller in any position, and a master controller for energizing either oi said magnets separately but not simultaneously or for denergizing rthem both, said master controller comprise ing a plurality oi push buttons.

21. ln combination, a motor, a main controller therefor biased to move in one direction, an electromagnet for moving said controller' unintcrruptedly in the other direction, a second electromagiiet for vholding said controller in any position, and a plurality ot master controllers 'forsaid electromagnets, each ot said master controllers comprising a plurality of push buttons.

22. in combination, a motor, a main controller therefor biased to move in one direction, an electromagnct for moving said controller in the other direction, a second electromagnet for holding` said controller in any position, and a pluralitaT of master controllers.

each comprising a y)lurality o'l push buttons, said master controllers being connected to energize either of said electromagnets separately or to denergize them both.

23. ln combination, a motor, a variable resistance in the armature circuit thereof, a controller arm for varying said resistance, said controller arm. being biasedl toward movement in one direction, an electronagnet for moving said arm in the other direction, a second electromagnet for holding said arm in any position, and a master controller for energizing either of said magnets separately but not both at once Vor for deenergizing them both and for controlling the motor circuit, said master vcontroller consisting ol" a plurality oi" push buttons.

In. combination, a motor, a main controller therefor biased in one direction, an

electroinagnet 'l'or moving said controller in 1 another direction, a second elcctromagnet for holding said controller in any position, and a plurality o'l push buttons i'or controlling said electroniagncts, said. push huttons heing so connected and arranged that when one ol them interrupts the circuits otI hoth electromagnets none ot the others will 4 he ahle to complete either olt said circuits.

2:3. .In combination, a motor, a controller therel'or biased in one direction, an electromagnet l'or moving said controller steadily in thc other direction, a second electromagnet 'for holding said cont/roller in any position against movement in either direction,

and push buttons for controlling said electromagnets.'

2G. ln combination, a main controller,'

a Way from said 'first contact and also moving said second contact so that the iirstpush cuit either directly or through the converter,

and a plurality ol master controllers for said main controller, from any one of which any desired operation of the main controller may be obtained at any time unless a more conservative operation is sought at another of said motor controllers.

35. fin combination, a motor, a source oi1 supply, a converter, a main controller arranged. to connect said motor to the source olZ supply either directly or through the converter and for varying the resistance ol: the motor armature circuit when such connection is direct, and a plurality ol: master controllers for said main controller, any one ol said motor controllers' being capable of cans'- ing any desired operation of the main controller except When a more conservative operation thereof is also sought.

29. In combination, a motor, a source ol supply, a converter, a main controller ar-` ranged to connect said motor to the source ol' supply either directly or through the con verter and for varying the resistance of the moto armature circuit when such connection is direct, and a push-button system ol control for said main controller.

30. In combination, a motor-,a source ol supply, a converter, a main controller ar-i ranged to connect said motor to the source ol supply either dircctlytcr through the converter and to vary the resistance of the motor armature circuit when the connection is direct and the voltage ol the converter secondl ary when such connection is through the con- I verter, and a plurality olY master controllers lor said ,main cmitrollcr, any one ol said master controllers being capahlc of causing any desired operation ol the main controller except when a more conservative operation is simultaneously sought.

51. Vln crnnhination, a motor, a source of supply, a comforter, a main controller arranged to connect said motor to the source of supply either directly or through the converter and to'vary the resistance olt the motor armature circuit when the connection is direct and the voltage ol' the converter secondary when such connection is through the converter, and a push-button system of control ior said main controller.

l 32. in combination, a motor, a source ol electromotive force, a converter, a main controller arranged to disconnect said motor or to connect it to said source either directly vor through the converter, and a push-button connecting said motor or for connecting it to i thereby, and a push-button system of coneither of said sources, and a push-Mitten systrol for said means. l0

tem of control for said means.. In testimony whereof I aEX my signature,

34. In combination, an electric motor, a plurality of'sourees of eleetromotive force, AWALTER J. RICHARDS. meansfor disconnecting said motor or for VitnesSes: connecting it to any of seid sources and vary- GEO. B. SCHLEY, ingthe potential impressednpon the motor FRED J. KINSEY.

in' the presence of two Witnesses. 

